I have to obtain from Nissan here a 'conformity file' which lists the complete specification per car and model. Customs can (if desired but in practice don't) compare a car to this but in fact, the valuation with photos serves as 'proof' of the car as OEM.
The same conformity file serves for the 'MOT' and ultimately is filed when final vehicule registration is performed.
How can you in the UK 'prove' that the car is OEM or otherwise or alternatively, how can the Customs prove that a car is otherwise ?
Do 'they' compare to Euro spec ?.....and if the imported car is not OEM USA spec....and (for the benefit of the Count) what if it is JDM or another RHD export destination country ?
Sounds like a bowl of pot-noodles to me.....